Evaluation of nutrient loads conveyed to the deep subalpine lakes of Northern Italy through their main tributaries
Nutrient pollution is a critical issue for lakes, leading to cultural eutrophication, which damages the ecosystem and prevents water uses. Proper watershed management practices must be put into action to effectively oppose eutrophication. Because of the complexities and the multiple layers of stakeh...
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Frontiers Media S.A.
2025-01-01
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| Series: | Frontiers in Environmental Science |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/fenvs.2025.1524250/full |
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| author | Paolo Dezuanni Paolo Dezuanni Diego Copetti Claudia Dresti Nicolò Pella Nicolò Pella Fabio Buzzi Andrea Fenocchi Andrea Fenocchi |
| author_facet | Paolo Dezuanni Paolo Dezuanni Diego Copetti Claudia Dresti Nicolò Pella Nicolò Pella Fabio Buzzi Andrea Fenocchi Andrea Fenocchi |
| author_sort | Paolo Dezuanni |
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| description | Nutrient pollution is a critical issue for lakes, leading to cultural eutrophication, which damages the ecosystem and prevents water uses. Proper watershed management practices must be put into action to effectively oppose eutrophication. Because of the complexities and the multiple layers of stakeholders involved in this process, the only factual way to evaluate improvements in watershed nutrient management is to directly estimate nutrient loads at watershed closing sections through available data from environmental monitoring. The Italian deep subalpine lakes (DSLs: Lake Como, Lake Garda, Lake Idro, Lake Iseo, Lake Maggiore) suffered from extensive eutrophication from the 1950s to the early 1980s. Their water quality improved in the 1980s and 1990s after national regulations were introduced to address nutrient pollution. After the turn of the century, increasingly pressing limits on nutrient disposal have been issued, yet steady if not worsening lake water quality conditions have been observed overall. To shed light on the issue, quantifying present and past external loads to these lakes based on direct measurements is essential. In this work, we focused on the main tributaries of the Italian DSLs, employing the observed time series of flowrate and nutrient concentrations to estimate the loading levels of nitrogen and phosphorus and their temporal evolution over a period ranging between 13 and 42 years according to data availability. The LOAD ESTimator (LOADEST) software was adopted to support the load quantification process. Results show that a general decrease in external nutrient loads is still occurring, albeit at a slow pace, the fastest reduction occurring for the Oglio River flowing into Lake Iseo, which has suffered from severe nutrient pollution till recently. Increasing loads have conversely been identified for the Sarca River flowing into Lake Garda. These outcomes highlight the beneficial actions carried out to reduce nutrient pollution, although a decorrelation analysis between external loads and flowrate is suggested for a clearer evaluation of its evolution across the DSLs. |
| format | Article |
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| institution | Kabale University |
| issn | 2296-665X |
| language | English |
| publishDate | 2025-01-01 |
| publisher | Frontiers Media S.A. |
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| series | Frontiers in Environmental Science |
| spelling | doaj-art-8dc7fb0dedb04e179c86819348e745f32025-01-24T07:13:25ZengFrontiers Media S.A.Frontiers in Environmental Science2296-665X2025-01-011310.3389/fenvs.2025.15242501524250Evaluation of nutrient loads conveyed to the deep subalpine lakes of Northern Italy through their main tributariesPaolo Dezuanni0Paolo Dezuanni1Diego Copetti2Claudia Dresti3Nicolò Pella4Nicolò Pella5Fabio Buzzi6Andrea Fenocchi7Andrea Fenocchi8Department of Civil Engineering and Architecture, University of Pavia, Pavia, ItalyNational Research Council, Water Research Institute (CNR-IRSA), Verbania, ItalyNational Research Council, Water Research Institute (CNR-IRSA), Brugherio, ItalyNational Research Council, Water Research Institute (CNR-IRSA), Verbania, ItalyDepartment of Civil Engineering and Architecture, University of Pavia, Pavia, ItalyNational Research Council, Water Research Institute (CNR-IRSA), Verbania, ItalyDepartment of Lecco, Regional Environmental Protection Agency of Lombardia (ARPA Lombardia), Oggiono, ItalyDepartment of Civil Engineering and Architecture, University of Pavia, Pavia, ItalyNational Research Council, Water Research Institute (CNR-IRSA), Verbania, ItalyNutrient pollution is a critical issue for lakes, leading to cultural eutrophication, which damages the ecosystem and prevents water uses. Proper watershed management practices must be put into action to effectively oppose eutrophication. Because of the complexities and the multiple layers of stakeholders involved in this process, the only factual way to evaluate improvements in watershed nutrient management is to directly estimate nutrient loads at watershed closing sections through available data from environmental monitoring. The Italian deep subalpine lakes (DSLs: Lake Como, Lake Garda, Lake Idro, Lake Iseo, Lake Maggiore) suffered from extensive eutrophication from the 1950s to the early 1980s. Their water quality improved in the 1980s and 1990s after national regulations were introduced to address nutrient pollution. After the turn of the century, increasingly pressing limits on nutrient disposal have been issued, yet steady if not worsening lake water quality conditions have been observed overall. To shed light on the issue, quantifying present and past external loads to these lakes based on direct measurements is essential. In this work, we focused on the main tributaries of the Italian DSLs, employing the observed time series of flowrate and nutrient concentrations to estimate the loading levels of nitrogen and phosphorus and their temporal evolution over a period ranging between 13 and 42 years according to data availability. The LOAD ESTimator (LOADEST) software was adopted to support the load quantification process. Results show that a general decrease in external nutrient loads is still occurring, albeit at a slow pace, the fastest reduction occurring for the Oglio River flowing into Lake Iseo, which has suffered from severe nutrient pollution till recently. Increasing loads have conversely been identified for the Sarca River flowing into Lake Garda. These outcomes highlight the beneficial actions carried out to reduce nutrient pollution, although a decorrelation analysis between external loads and flowrate is suggested for a clearer evaluation of its evolution across the DSLs.https://www.frontiersin.org/articles/10.3389/fenvs.2025.1524250/fullLOADEST regression modelDSLphosphorus and nitrogen external loadslong-time series analysiscatchment nutrient pollutionflow discharge |
| spellingShingle | Paolo Dezuanni Paolo Dezuanni Diego Copetti Claudia Dresti Nicolò Pella Nicolò Pella Fabio Buzzi Andrea Fenocchi Andrea Fenocchi Evaluation of nutrient loads conveyed to the deep subalpine lakes of Northern Italy through their main tributaries Frontiers in Environmental Science LOADEST regression model DSL phosphorus and nitrogen external loads long-time series analysis catchment nutrient pollution flow discharge |
| title | Evaluation of nutrient loads conveyed to the deep subalpine lakes of Northern Italy through their main tributaries |
| title_full | Evaluation of nutrient loads conveyed to the deep subalpine lakes of Northern Italy through their main tributaries |
| title_fullStr | Evaluation of nutrient loads conveyed to the deep subalpine lakes of Northern Italy through their main tributaries |
| title_full_unstemmed | Evaluation of nutrient loads conveyed to the deep subalpine lakes of Northern Italy through their main tributaries |
| title_short | Evaluation of nutrient loads conveyed to the deep subalpine lakes of Northern Italy through their main tributaries |
| title_sort | evaluation of nutrient loads conveyed to the deep subalpine lakes of northern italy through their main tributaries |
| topic | LOADEST regression model DSL phosphorus and nitrogen external loads long-time series analysis catchment nutrient pollution flow discharge |
| url | https://www.frontiersin.org/articles/10.3389/fenvs.2025.1524250/full |
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